1. Field of the Invention
The present invention relates to a computer system and, more particularly, to a method and circuit for adjusting the background contrast in a display device.
2. Description of the Related Art
In general, a television is designed to display low resolution images while a display device, e.g., a computer monitor, is designed to display high resolution images. A television displays moving images while a computer monitor, e.g., a color display tube (CDT), displays still images or text. Multimedia data may include text, photographs, moving images, and games. A conventional computer monitor is designed to display text images with lower contrast and sharpness than a television screen. Thus, computer monitors do not optimally display moving images.
Typically, a user selects a desired partial screen (hereinafter, referred to as a ‘partial region’) from the entire screen displayed on a CDT in order to view a moving image. When contrast and sharpness are increased in both a text displaying region and a non text displaying region of a CDT, the text displaying region of a CRT might be physically damaged.
Unlike a television color picture tube (CPT) that displays various moving images by adjusting the contrast and sharpness of a desired partial region, a conventional CDT does not provide the enhanced sharpness and necessary clarity for effectively displaying moving images.
Even if the contrast and sharpness of the partial region are increased, if the contrast of an outer, background, region is high (that is, if brightness of the background region is high), the partial region contrast cannot be decreased.